There is known a fixing device including a metal sleeve having a cylindrical shape, a ceramic heater positioned at an internal space of the metal sleeve, and a pressure roller for nipping the metal sleeve in cooperation with the ceramic heater. The ceramic heater has a sliding surface in sliding contact with the metal sleeve, and an entire surface of the sliding surface is coated with an imide series resin such as polyimide so as to prevent an inner surface of the metal sleeve from wearing by the ceramic heater.